Properties of the Number 21421

Twenty-One Thousand Four Hundred Twenty-One

Basics

Value: 21420 → 21421 → 21422

Parity: odd

Prime: No

Previous Prime: 21419

Next Prime: 21433

Digit Sum: 10

Digital Root: 1

Palindrome: No

Factorization: 31 × 691

Divisors: 1, 31, 691, 21421

Polygonal

Triangular: No

Square: No

Pentagonal: No

Hexagonal: No

Heptagonal: No

Tetrahedral: No

Today's Target

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Representations

Binary: 101001110101101

Octal: 51655

Duodecimal: 10491

Hexadecimal: 53ad

Square: 458859241

Square Root: 146.35914730552375

Classification

Fibonacci: No

Bell Number: No

Factorial Number: No

Regular Number: No

Perfect Number: No

Special

Kaprekar Constant: No

Munchausen Constant: No

Armstrong Number: No

Kaprekar Number: No

Catalan Number: No

Vampire Number: No

Taxicab Number: No

Super Prime: No

Friedman Number: No

Fermat Number: No

Cullen Number: No

OEIS Sequences

a(n) = numerator((ζ(2, 1/3) - ζ(2, n + 1/3))/9), where ζ(n, z) is the Hurwitz ζ function. A173983

Semiprimes in A003215. A113530

a(n) = 1 + n*(n+1)*(n-1)/2. A158842

Centered 36-gonal numbers. A195316

a(n) = ∑_{k=0..floor(2·n/5)} binomial(k,2·n-5·k). A391265

Constant term in the expansion of (1 + x² + y² + 1/(x·y))ⁿ. A361657

Number of compositions of 6·n-4 into parts 5 and 6. A373964

Numerators of continued fraction convergents to sqrt(526). A42006

Semiprime centered triangular numbers. A184481

Numbers k such that w(k), w(k+1), and w(k+2) are all odd, where w is A360519. A361106